1. Field of the Invention
The present invention relates to a fastening device and a method for fastening an element in a keyhole-shaped cutout in a wall.
2. Description of the Related Art
Components, in particular sensors (for restraint systems, for example), are fastened to the vehicle in various ways in the automotive industry. In addition to screwing to a nut welded into the body, or screwing with the aid of a screw through a hole in the body and into a threaded bushing of the component, the “keyhole principle” is used for fastening housings. A bolt which is preinstalled'in the housing together with a self-locking nut is inserted into the larger portion of a keyhole-like hole in the body panel of the vehicle, and is then suspended in the lower, narrower portion of the keyhole. The nut is then tightened, thus securely clamping the component.
Compared to the two other methods mentioned above, the keyhole principle has the advantage that a welded-in or preinstalled nut in the vehicle is not required, which represents a significant cost advantage. The keyhole principle also allows so-called “one-hand installation,” and its use is therefore very popular in some cases, for example in installation areas which are difficult to access.
However, during installation the component may twist in the keyhole if appropriate anti-twist protection is not provided. The sensor cannot be guaranteed to fulfill its function if it twists during installation.
A component is known from published European patent document EP 1 532 372 which has anti-twist protection for installation in a keyhole-shaped cutout. However, the component must first be inserted into the keyhole and secured therein in order for the anti-twist protection to become effective.